When a C++ project is named Test on a Binary version of the editor, the project will fail to compile. I'm assuming this is from the editor seeing a precompiled header from another file in the engine called Test.h.
This also occurs with projects named "Core"
Update
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Performing a non-hot reload build in Visual Studio will complete successfully.
Result: The initial compilation fails and shows the following message:
The project could not be compiled. Would you like to open it in Visual Studio?
Running D:/Epic Games/4.15/Engine/Binaries/DotNET/UnrealBuildTool.exe Test Development Win64 -project="D:/Unreal Projects/Current Issues/Test/Test.uproject" -editorrecompile -progress -NoHotReloadFromIDE
Performing full C++ include scan (building a new target)
ERROR: System.NotSupportedException: The given path's format is not supported.
at System.Security.Permissions.FileIOPermission.QuickDemand(FileIOPermissionAccess access, String fullPath, Boolean checkForDuplicates, Boolean needFullPath)
at System.IO.FileInfo.Init(String fileName, Boolean checkHost)
at UnrealBuildTool.UnrealBuildTool.LoadUBTMakefile(FileReference MakefilePath, FileReference ProjectFile, String& ReasonNotLoaded)
at UnrealBuildTool.UnrealBuildTool.RunUBT(String[] Arguments, FileReference ProjectFile)
Expected: Either this should be possible or the Unreal Project Launcher should prevent the project from being named Test
Head over to the existing Questions & Answers thread and let us know what's up.